Drozd , Yu. A., and L. V. Izyumchenko. “Representations of Ɗ-Kinds”. Ukrains’kyi Matematychnyi Zhurnal 44, no. 4 (April 17, 1992): 572–574. Accessed December 6, 2025. https://umj.imath.kiev.ua/index.php/umj/article/view/7904.